Question about Comcast HD PPV for UFC 127 tonight

Hey guys, wanted to see if anyone else in FL uses comcast to buy the UFC events. This is our first time trying to do it, and I don't see an option for HD. I spoke to a woman who had no clue what she was talking about so I thought I'd ask here. Anyone know how this works? Thanks!

its a little late now but its channel 509 i think it is and regular is 504 (not hd)